The present invention relates to power delivery systems and more specifically to floor assemblies for delivering power to furniture components that are supported by the floor irrespective of the location of the furniture component on the supporting floor structure.
A large number of different powered components and devices have been developed that require electrical power to perform various functions. Exemplary powered components include lights, phones, ovens, computers, motors, coffee makers, radios, televisions, printers, fax machines, copiers, etc. The conventional way to deliver power to powered components has been to attach a separate electrical cord for each of the components where the cord includes a male connector that is received in a female wall or floor mounted outlet. Thus, where ten separate powered components are located on a table, ten separate cords have been required for power delivery.
While cords perform the primary power delivery function well, unfortunately corded power delivery has several shortcomings. First, cords necessarily tether powered components to outlets and therefore restrict movement of associated components within a space.
Second, cords in general are unsightly. In this regard, most cords are provided in lengths that are usable for various applications. Thus, for instance, a ten foot power cord may be provided so that a powered component can be plugged into an outlet and located anywhere within a ten foot distance of the outlet. Here, while the ten foot length allows flexible placement of the powered component, often less than ten feet of cord is required (e.g., where the component is located three feet from an outlet) and the excess cord is simply heaped together between the component and the outlet. Unsightliness of power cords is exacerbated when multiple (e.g., ten) powered components are located in a small space.
Third, where several power cords are located proximate each other, often the cords become tangled and the process of determining which cord is associated with which component becomes confusing and time consuming.
Fourth, some cords have to be placed in locations where they restrict movement. For instance, where a cord has to be strung across a walkway to reach an outlet, the cord can present an obstacle for people passing by in the walkway.
Fifth, cords can become unplugged. In some cases when a cord becomes unplugged, the cord can simply be re-plugged into an outlet to resume operation of the powered component (e.g., in the case of a lamp). In other cases, however, unplugging can have an adverse effect on the workflow of a person using the component. For instance, in the case of a computer that stores data, unplugging can cause the loss of data and can require a rebooting process that is time consuming.
One solution to the power cord problems has been to provide batteries for powered components where the batteries move along with the components. The main problem with batteries is that batteries either have to be routinely replaced or need to be recharged periodically. For example, in the case of a laptop computer battery, most laptop batteries do not last more than three or four hours without a recharge.
Another solution to the power cord problems has been to provide an area power system that delivers power to powered components irrespective of the locations of those components within a “power area”. For example, one known solution includes a system wherein stationary conductors are provided in an array adjacent a power area and where a powered component (a laptop computer, etc.) includes pickup contacts that slide across and make contact with the stationary conductors so that the conductors can provide power to the component. Here, in at least some embodiments, the power conducting system includes scanning switching devices that can be used to turn on power to specific conductors after a controller determines that the stationary conductors are in contact with pickup contacts on a powered component. The pattern and dimensions of the stationary power conductors are designed such that the pickup contacts make contact with at least two of the stationary conductors at all times.
To determine if a powered component currently contacts a pair of the stationary power conductors so that power should be supplied to the stationary conductors, each powered component includes an identification load (e.g., a resistor) and that separate low current signals are sequentially provided to each of the power conductors. When two of the pickup contacts on the powered component contact two of the stationary power conductors when a low current signal is applied via the scanning switching devices to one of the contacted stationary conductors, the low current passes through the identification load and returns to the power system through the second contacting stationary conductor. The returning current is used to read the identifying load and hence to determine that a component to be powered is linked to the two stationary conductors (i.e., to the conductor that the low current was provided to and to the conductor through which the current returned to the power system). Once the two contacting stationary conductors are identified, power is delivered through those conductors to the powered component.
Power area solutions have at least two shortcomings. First, the switching devices contemplated for scanning for and then providing higher current levels to electrical loads (i.e., to powered components) are complex and therefore would be expensive to configure. While expensive switching devices may be suitable in some applications used to charge small electronic devices (e.g., cellular phones, PDAs, etc.) where a small charging mat or the like can provide a sufficiently sized power area, where a larger power area is required, such complex switching devices would be prohibitively expensive in most applications.
Second, the number of switching devices required to link load contacts to either positive voltage or ground is large (i.e., at least one switching device is required per mat contact plate).